Fuel injection system

ABSTRACT

In a fuel injection system including at least one fuel injector which includes an inflow section and a fuel distributor line which includes for each fuel injector a coupling connection, an annular gasket support is provided for a sealing connection of the inflow section with the coupling connection; this gasket support cooperates with a first sealing element for sealing the gasket support from an end face of the inflow section and includes a second sealing element for sealing the gasket support from the coupling connection. A guide section of the inflow section passes through the gasket support, and a retaining ring is provided on the inflow section secures the gasket support so that it is movable in the radial direction between the retaining ring and the end face.

FIELD OF THE INVENTION

The present invention relates to a fuel injection system for injectingfuel into an internal combustion engine, e.g., for direct injection offuel into the combustion chamber(s) of the engine.

BACKGROUND INFORMATION

Such a fuel injection system is described in German Published PatentApplication No. 197 25 076. For a sealing connection between a fuelinjector and a respective coupling connection of a fuel distributorline, this injection system includes an annular gasket support whichcooperates with a first sealing element for sealing off the gasketsupport from an end face of an inflow section of the fuel injector andincludes a second sealing element for sealing off the gasket supportfrom the coupling connection of the fuel distributor line. A bushinginsertable into a fuel inlet opening of the inflow section passesthrough the annular gasket support, so that the gasket support ismovably arrested in the radial direction between an upstream collar ofthe bushing and the inflow section of the fuel injector.

One disadvantage of the arrangement described in the publication citedabove is that the bushing is an additional part which is manufacturedwith a low tolerance. The radial mobility of the gasket support isguaranteed only if it still has a certain axial play and is not pressedby the bushing against the inflow section, so the bushing is inserted toa precisely defined depth into the fuel inlet opening in assembly. Thisrequires a precision finished cylindrical surface of the bushing and abore produced with a corresponding fit as the fuel inlet opening inorder to achieve a tight seating of the bushing, so that the requiredplay for the gasket support is adjustable.

It is described in Unexamined Japanese Published Patent No. 08-312503that a fuel injector insertable into a receiving bore and including aninflow section may be sealed by an O-ring on this inflow section withrespect to a coupling connection of a fuel distributor line. The O-ringis in sealing contact with an inside wall of the coupling connection.

Due to the manufacturing tolerance of the receiving bore for the fuelinjector as well as that of the coupling connection to the fueldistributor line, differences in position and angle occur between theinflow section of the fuel injector and the coupling connection of thefuel distributor. The O-ring situated between the inflow section of thefuel injector and the coupling connection of the fuel distributor lineequalizes the differences in position and angle only to a very slightextent, which is inadequate. With regard to the differences in positionand angle occurring in practice, in the case of the fuel injector systemdescribed in Unexamined Japanese Published Patent No. 08-312503, thereis a risk of fuel escaping past the seal, which does not adequatelycompensate for the position and angle differences.

SUMMARY OF THE INVENTION

The fuel injection system according to the present invention may providethe advantage that the O-rings used for sealing need not compensate forthe position and angle differences through a purely elastic deformation.The O-rings are not deformed on one side. The fuel injection systemaccording to the present invention may provide the advantage thatadditional components in the form of bushings which requires precisionmanufacturing are eliminated. In addition, the fuel injector need notinclude an inflow bore finished to fit. Therefore, the manufacturingcomplexity of these parts may be reduced and thus the manufacturingcosts lowered accordingly.

It may be advantageous if the first sealing element is guided in a firstring groove in a downstream, radially aligned end face of the gasketsupport and is slidingly movable in the radial direction on the end faceof the inflow section of the fuel injector.

It may be advantageous if the first sealing element is guided in a firstring groove in the end face of the inflow section of the fuel injectorand is slidingly movable in the radial direction on a downstream endface of the gasket support which is aligned radially. The shape of thesealing element is thereby simplified. The additional ring groove in theend face of the inflow section of the fuel injector is less expensive tomanufacture by comparison because precision machining by lathing theparts of the fuel injectors is required in any case.

It may be advantageous if an upper and/or lower supporting ring having alarger outside diameter than the gasket support is provided downstreamfrom the second sealing element in the second ring groove and is freelymovable radially. Thereby, excess deformation of the O-ring andresulting leakage of the fuel injection system may be prevented.

Advantageously the retaining ring may be weldable to the inflow sectionor held in a groove of the inflow section in a simple manner.Manufacturing complexity is greatly reduced when the retaining ring isguided in a groove, because care must be taken to ensure the position ofthis ring groove only in manufacturing the parts of the fuel injector,which in any case is done with a low tolerance.

Example embodiments of the present invention are shown in simplifiedform in the drawings and explained in greater detail in the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a section through an example embodiment according to thepresent invention in a detail of a diagram of the connecting areabetween the fuel injector and the fuel distributor line.

FIG. 2 shows a section through another example embodiment according tothe present invention in a detail of a diagram of the connecting areabetween the fuel injector and the fuel distributor line.

FIG. 3 shows another example embodiment of a fuel injection systemaccording to the present invention in a detail corresponding to detailIII of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows an example embodiment of the present invention in a detailof a sectional diagram. Only the coupling connection area between a fuelinjector 1 and a fuel distributor line 2 is shown. Fuel distributor line2 is shown here only in the area of a coupling connection 3.

Fuel injector 1 includes an inflow section 4 including a guide section 5which is configured in one piece with inflow section 4 of fuel injector1. An end face 6 is configured on inflow section 4 at a transition toguide section 5. Along a central axis 7 of fuel injector 1, an inflowbore 8 for fuel passes through guide section 5 and inflow section 4. Agasket support 9 includes a guide section 5 passing through it and islocked between inflow-side end face 6 of inflow section 4 and aretaining ring 10 situated on the inflow end of guide section 5 andprojecting radially outward. Retaining ring 10 is situated on guidesection 5 of fuel injector 1 with an axial distance a from end face 6,shown here for the sake of illustration so that gasket support 9 isaxially movable with a play b to a slight extent. Gasket support 9 isthus not clamped between retaining ring 10 of guide section 5 and inflowsection 4 of fuel injector 1 but instead is radially movable within adisplacement area c, which is also shown for the sake of illustration,in the radial direction.

Gasket support 9 includes a radially aligned end face 11 opposite endface 6 of inflow section 4 of fuel injector 1 on its downstream end. Afirst peripheral ring groove 12 is provided on gasket support 9 and isused to accommodate and guide a first sealing element 13 in the form ofa sealing ring configured as an O-ring. First sealing element 13functions as an axial seal and seals off gasket support 9 from inflowsection 4 of fuel injector 1. First sealing element 13 is slidinglymovable on end face 11 of inflow section 4 of fuel injector 1.

Furthermore, gasket support 9 includes a second ring groove 16 on alateral surface 15 opposite a wall 14 of coupling connection 3. Secondring groove 16 is used to accommodate and guide a second sealing element17 in the form of a sealing ring configured as an O-ring. Second sealingelement 17 produces a radial seal and seals off gasket support 9 fromcoupling connection 3. Second sealing element 17 is slidinglydisplaceable in coupling connection 3.

In an example embodiment, retaining ring 10 is inserted into a ringgroove 18 in guide section 5 of inflow section 4 of fuel injector 1.Retaining ring 10, when configured as an open ring, may be installedeasily by being spread by a suitable tool and pushed over guide section8. Due to the internal stress of retaining ring 10, it is held in ringgroove 18. When gasket support 9 is acted upon by fuel pressure inoperation, the entire upstream end face 6 of gasket support 9 up to itsoutside diameter is thus available on the upstream side as a workingsurface for fuel pressure. However, gasket support 9 is exposed to thefuel pressure on its downstream end at the most up to first sealingelement 13 because the area further toward the outside radially issealed. Gasket support 9 is therefore acted upon by an effective axialforce component through the fuel pressure, pressing gasket support 9 inthe direction of fuel injector 1. First sealing element 13 is thereforepressed against end face 6 of inflow section 4 of fuel injector 1,resulting in a good sealing effect.

Annular gasket support 9 may advantageously permit a radial equalizationas well as an axial equalization between the position of inflow section4 of fuel injector 1 and the position of coupling connection 3. Thisinexpensive, easy-to-manufacture configuration of the components may beadvantageous. Inflow section 4 of fuel injector 1 is manufactured to ahigh precision, like all parts of fuel injector 1, and may be machinedby lathing. The configuration of a guide section 5 including a ringgroove 18 cut in it constitutes an increased expense, although it isalmost insignificant. Only a single size, namely the distance a betweenring groove 18 and end face 6, need be maintained with precision. Thispermits great cost savings in comparison with an additional componentand a bore to be made to fit.

FIG. 2 shows another example embodiment of a fuel injection systemaccording to the present invention in a detail of a cut-away diagram. Asin FIG. 1, the connection area between a fuel injector 19 and a fueldistributor line 20, of which only a coupling connection 21 is visiblehere, is shown. Fuel injector 19 includes an inflow section 22 which isconfigured in one piece with a guide section 23.

An end face 24 is configured on inflow section 22 at the transition to aguide section 23. An inflow bore 26 for fuel passes through guidesection 23 and inflow section 22 along a central axis 25 of fuelinjector 19. A gasket support 27 includes guide section 23 passingthrough it and is locked between inflow-side end face 24 of inflowsection 22 and a retaining ring 26 which projects radially outward andis situated on the inflow end of guide section 23. Retaining ring 28 isconnected by peripheral weld 29 to guide section 23 in the exampleembodiment shown here as an example.

Gasket support 27 is not clamped between retaining ring 28 of guidesection 23 and inflow section 22 of fuel injector 19 due to thearrangement of retaining ring 28 according to FIG. 1, but instead ismovable in the radial direction. On its downstream end, gasket support27 includes a radially aligned end face 30 opposite end face 24 ofinflow section 22 of fuel injector 19.

A first peripheral ring groove 31 is configured in end face 24 of inflowsection 22 to receive and guide a first sealing element 32 in the formof an O-ring. First sealing element 32 seals the gasket support 27 in aslidingly movable manner from inflow section 22 of fuel injector 19.

In addition, gasket support 27 includes a second ring groove 35 on alateral face 34 opposite a wall 33 of coupling connection 21. A secondsealing element 36 in the form of an O-ring is guided in second ringgroove 35. Slidingly movable second sealing element 36 radially sealsoff gasket support 27 from coupling connection 21.

It may be advantageous in this example embodiment that gasket support 27is further simplified in that first ring groove 31 is situated in endface 24 of fuel injector 19. First ring groove 31 is produced on fuelinjector 19 more easily and less expensively. Functioning is in nomanner impaired by the fact that first sealing element 32 is notpositioned in end face 30 of gasket support 27 but instead in end face24 of inflow section 22 of fuel injector 19.

FIG. 3 shows another example embodiment of a fuel injection systemaccording to the present invention in a detail according to detail IIIin FIG. 1. This example embodiment differs from fuel injector 1 in FIG.1 only in this detail. Therefore, the same reference numbers are usedfor the same parts.

Gasket support 9 is shown in a sectional diagram, illustrating firstring groove 12 including first sealing element 13. Second sealingelement 17 is guided in second ring groove 16. In an example embodiment,a supporting 37 is situated downstream from second sealing element 17,which is configured as an O-ring. The inside diameter of supporting ring37 is such that it does not extend to the bottom of second ring groove16 and consequently it is radially movable.

Due to this configuration, the outside diameter of gasket support 9 mayhave a smaller dimension, and sealing element 17 may be exposed togreater tilting angles without undergoing inadmissible deformation.

An upper supporting ring including a larger outside diameter than gasketsupport 9 is provided upstream from second sealing element 17 and isguided in second ring groove 16 and with free radial mobility. Gasketsupport 9 includes a conical radial chamfer on its upstream end.

1-11. (canceled)
 12. A fuel injection system for injecting a fuel intoan internal combustion engine, comprising: at least one fuel injectorthat includes an inflow section; a fuel distributor line that includes,for the at least one fuel injector, a coupling connection connectable tothe inflow section; an annular gasket support for providing a sealingconnection of the inflow section to the coupling connection; a firstsealing element that cooperates with the annular gasket support to sealoff the annular gasket support from an end face of the inflow section; asecond sealing element for sealing off the annular gasket support fromthe coupling connection; a guide section included in the inflow sectionand passing through the annular gasket support; and a retaining ringincluded on the inflow section upstream from the annular gasket supportso that the annular gasket support is secured movably in a radialdirection between the retaining ring and the end face of the inflowsection.
 13. The fuel injection system according to claim 12, wherein:the first sealing element is guided in a first ring groove in adownstream, radially oriented end face of the annular gasket support andis slidingly movable in the radial direction on the end face of theinflow section.
 14. The fuel injection system according to claim 12,wherein: the first sealing element is guided in a first ring groove inthe end face of the inflow section and is slidingly movable in theradial direction on a downstream, radially oriented end face of theannular gasket support.
 15. The fuel injection system according to claim13, wherein: a gap remains between the end face of the inflow sectionand the end face of the annular gasket support due to an arrangement ofthe retaining ring and an elasticity of the first sealing element evenwhen acted upon by the fuel under pressure.
 16. The fuel injectionsystem according to claim 12, wherein: the second sealing element isguided in a second ring groove of an axially oriented lateral surface ofthe annular gasket support and is slidingly movable in an axialdirection on a wall of the coupling connection.
 17. The fuel injectionsystem according to claim 16, further comprising: a lower supportingring arranged downstream from the second sealing element and having alarger outside diameter than the annular gasket support, the lowersupporting ring being guided in a radially freely movable manner in thesecond ring groove.
 18. The fuel injection system according to claim 16,further comprising: an upper supporting ring having a larger outsidediameter than the annular gasket support, the upper supporting ringbeing guided in a radially freely movable manner in the second ringgroove upstream from the second sealing element.
 19. The fuel injectionsystem according to claim 12, wherein: the annular gasket supportincludes a conical radial chamfer arranged on a periphery of an upstreamend of the annular gasket support.
 20. The fuel injection systemaccording to claim 12, wherein: the retaining ring is welded to theinflow section.
 21. The fuel injection system according to claim 12,further comprising: wherein the retaining ring is held in a groove ofthe inflow section.
 22. The fuel injection system according to claim 12,wherein: the first sealing element and the second sealing element areconfigured as peripheral ring seals.